Reduction gear device with differential gear mechanism for electric vehicle

Abstract

A reduction gear device with a differential gear mechanism 4 for an electric vehicle, has a planetary gear type reduction gear mechanism 3 for transmitting a power from an electric motor 2 to right and left wheels 6, 6 of the vehicle through the differential gear mechanism 4. The reduction gear mechanism 3 is contained in a casing 1, while either of output shafts 4a, 4b of the differential gear mechanism 4 penetrates an output shaft 2c of the electric motor 2. The reduction gear mechanism 3 comprises a plural of complex pinions P each formed by integrating a first pinion P1 and a second pinion P2 having a less number of teeth than that of the first pinion P1, a planetary carrier C3 connected to the output shaft 2c of the electric motor 2 and rotatably supporting each of the complex pinions P at certain positions on a common circle, a first ring gear R1 fixed onto the casing 1 and engaged with the first pinion P1 of each of the complex pinions P, and a second ring gear R2 engaged with the second pinion P2 of each of the complex pinions P and serving to transmit the power from the electric motor 2 to the differential gear mechanism 4. When utilizing a small size motor of high speed type as the electric motor 2, the reduction gear device can reduce a size of the device and simplify a construction of the device, while increasing a reduction ratio thereof.

I claim: 
     
       1. A reduction gear device for a vehicle having an electric motor, including a differential gear mechanism and a planetary gear type reduction gear mechanism, the differential gear mechanism being connected to a right wheel and a left wheel of the vehicle respectively through two output shafts, said reduction gear mechanism being contained in a casing mounted on the vehicle and transmitting power from the electric motor to the right and left wheels through the differential gear mechanism, an output shaft of the electric motor being penetrated by one of the output shafts of the differential gear mechanism, wherein said reduction gear mechanism comprises: a plurality of complex pinion assemblies each including a first pinion having a first number of teeth and a second pinion having a second number of teeth, said second number of teeth being less than said first number of teeth, said first and second pinions being integrated with each other;   a planetary carrier connected to said output shaft of said electric motor and rotatably supporting said complex pinion assemblies at positions spaced radially from a rotating axis of said planetary carrier by an equal amount and spaced from each other by a predetermined angle;   a first ring gear fixed to said casing and engaged with said first pinion of each of said complex pinion assemblies; and   a second ring gear engaged with said second pinion of each of said complex pinion assemblies and serving to transmit power from said electric motor to said differential gear mechanism.   
     
     
       2. A reduction gear device for an electric vehicle according to claim 1, wherein said differential gear mechanism is of a double pinion planetary gear type, and comprises a ring gear, a planetary carrier and a sun gear, said ring gear receiving power from said second ring gear of said reduction gear mechanism, and said planetary carrier and said sun gear transmitting power to the right and left wheels. 
     
     
       3. A reduction gear device for an electric vehicle according to claim 2, wherein said second ring gear of said reduction gear mechanism and said ring gear of said differential gear mechanism consist of a common ring gear. 
     
     
       4. A reduction gear device for a vehicle having two electric motors, including a differential gear mechanism and two planetary gear type reduction gear mechanisms, the differential gear mechanism having two output shafts through which the differential gear mechanism is connected to a right wheel and a left wheel of the vehicle respectively, the two reduction gear mechanisms being contained in a casing mounted on the vehicle, each of the two reduction gear mechanisms transmitting power from an adjacent one of the two electric motors to the right and left wheels through the differential gear mechanism; wherein said two electric motors occupy opposite ends of an inner space of said casing respectively,   said differential gear mechanism occupies a center of said inner space of said casing,   an output shaft of each of said electric motors is penetrated by an adjacent one of said two output shafts of said differential gear mechanism,   each of said two reduction gear mechanisms is placed between said differential gear mechanism and said adjacent one of the two electric motors, and comprises:   a plurality of complex pinion assemblies each including a first pinion having a first number of teeth and a second pinion having a second number of teeth, said second number of teeth being less than said first number of teeth, said first and second pinions being integrated with each other;   a planetary carrier connected to said output shaft of said adjacent one of the two electric motors and rotatably supporting said complex pinion assemblies at positions spaced radially from a rotating axis of said planetary carrier by an equal amount and spaced form each other by a predetermined angle;   a first ring gear fixed to said casing and engaged with said first pinion of each of said complex pinion assemblies;   a second ring gear engaged with said second pinion of each of said complex pinion assemblies and serving to transmit power from said adjacent one of said two electric motors to said differential gear mechanism; and   said differential gear mechanism is of a double pinion planetary gear type, and comprises a ring gear, a planetary carrier and a sun gear, said ring gear receiving power from said second ring gears of said two reduction gear mechanisms, and said planetary carrier and said sun gear transmit power to said right and left wheels.   
     
     
       5. A reduction gear device for an electric vehicle according to claim 4, wherein said second ring gears of said two reduction gear mechanisms and said ring gear of said differential gear mechanism consists of a common ring gear.